U.S. Fish and Wildlife officials (pictured above with Sen. Kent
Conrad (D-N.D.), second from right, and Rep. Earl Pomeroy (D-N.D.), right, release an adult pallid sturgeon into the confluence of the Missouri and Yellowstone rivers. For the past 50 years, the species has been able to survive - individuals live for up to 70 years - but not breed. Dams constructed from the 1930s to the 1950s cooled and clarified the warm, muddy water the pallid sturgeon needs to reproduce.

In 1988, the Club successfully petitioned to have the fish listed as endangered, and Fish and Wildlife started researching a captive breeding program to replenish the dwindling population. Says Kirk Koepsel, the Club's Northern Plains regional representative (he's standing just outside the frame of this photograph), "This is a good first step. The agency has bought itself the time to research habitat modifications the species needs to be able to breed."
http://www.sierraclub.org/planet/199809/fish.asp